PIC18F2480 MICROCHIP [Microchip Technology], PIC18F2480 Datasheet - Page 336

• Manufacturer Part Number: PIC18F2480
• Description: 28/40/44-Pin Enhanced Flash Microcontrollers with ECAN Technology, 10-Bit A/D and nanoWatt Technology
• Manufacturer: MICROCHIP [Microchip Technology]

PIC18F2480/2580/4480/4580
Table 23-3 shows the relation between the clock
generated by the PLL and the frequency error from
jitter (measured jitter-induced error of 2%, Gaussian
distribution, within 3 standard deviations), as a
percentage of the nominal clock frequency.
TABLE 23-3:
TABLE 23-4:
DS39637A-page 334
40 MHz
24 MHz
16 MHz
Output
Nominal PLL Output
PLL
40 MHz
24 MHz
16 MHz
0.83 ns
1.25 ns
0.5 ns
P
jitter
FREQUENCY ERROR FROM JITTER AT VARIOUS PLL-GENERATED CLOCK SPEEDS
TOTAL FREQUENCY ERROR AT VARIOUS PLL-GENERATED CLOCK SPEEDS
(100 PPM OSCILLATOR DRIFT, INCLUDING ERROR FROM JITTER)
1.67 ns
2.5 ns
T
(125 Kb/s)
1 ns
0.01209%
0.01313%
0.01125%
jitter
8 s
Frequency Error at Various Nominal Bit Times (Bit Rates)
(125 Kb/s)
0.00125%
0.00209%
0.00313%
8 s
Frequency Error at Various Nominal Bit Times (Bit Rates)
Preliminary
(250 Kb/s)
0.01250%
0.01418%
0.01625%
4 s
This is clearly smaller than the expected drift of a
crystal oscillator, typically specified at 100 ppm or
0.01%. If we add jitter to oscillator drift, we have a total
frequency drift of 0.0132%. The total oscillator
frequency errors for common clock frequencies and bit
rates, including both drift and jitter, are shown in
Table 23-4.
(250 Kb/s)
0.00250%
0.00418%
0.00625%
4 s
(500 Kb/s)
0.015%
0.018%
0.023%
2 s
(500 Kb/s)
0.005%
0.008%
0.013%
2 s
 2004 Microchip Technology Inc.
(1 Mb/s)
0.027%
0.035%
0.02%
(1 Mb/s)
1 s
0.017%
0.025%
0.01%
1 s